Although the use of a spiked tire and the installation of a chain on a tire have been carried out as running on snow and ice road surface, a studless tire is developed as a tire for running on snow and ice road surface in place of this because environmental problem such as dust problem is generated. Since friction coefficient is remarkably lowered on snow and ice road and tires slide easily in comparison with a general road surface, devices on materials and design have been carried out for a studless tire and a studless tire excellent in braking performance on ice has been developed.
In Japanese Unexamined Patent Publication No. 08-104777, there is disclosed a rubber composition for a tire using rubber vulcanization system comprising sulfur as a vulcanizing agent and a vulcanization accelerator in combination with an organic peroxide, in order to improve steering stability, fuel consumption saving and abrasion resistance. However, since the adjustment of vulcanization speed is difficult, there remains problem that it is not generally used yet.
In Japanese Unexamined Patent Publication No. 2001-279025, there are disclosed the production process of a rubber product, wherein vulcanization reaction is accelerated by (1) coating core materials comprising vulcanization components with a resin composition containing magnetic metal powder to obtain granules, (2) mixing the granules with rubber components to obtain a rubber composition, (3) heating the rubber composition with electromagnetic induction and (4) dissolving the resin composition to disperse vulcanization components in the rubber components of the rubber composition, and the rubber product obtained by the production process. However, there remains problem that productivity is inferior because steps increase.